When an operator (or driver) manipulates a shift lever in a manual transmission vehicle, shifting force is transmitted to a transmission gear box to shift a gear. In a small compact car, this shifting force is typically transmitted via a cable. However, in heavy-duty vehicles such as buses, trucks or the like, the shifting force is transmitted to the transmission via a plurality of link members. This is because the components to be shifted are large and heavy, and the distance covered by the shifting force is relatively far.
Conventionally, in order to transmit a shifting force from a driver to the transmission, two separate forces, applied in two directions, are required. These forces are combined to shift the transmission into gear in multiple stages. In other words, two forces are respectively transmitted to the transmission. One force selects the operation, where a shift lever is manipulated to left and/or right directions from a driver's seat to select one of the 1 or 2, 3 or 4 and 5 or R gears. The second force shifts into gear where the shift lever is manipulated forward or backward to shift into the selected gear. Typically, the forces are transmitted to the transmission via respective link structures where two different link structures are required to shift the transmission into gear from a shift lever to the transmission.
Such manual shifting devices, however, require two almost identically-structured link members, thereby increasing the number of parts, making it more difficult to operate, increasing maintenance, and decreasing the effect of the shifting force.